Sixteen-year-old Laurence Willshire, who used to weigh about 133 kg, has shed about 25 kg since he turned to the talking computer called mandometer.
The computer is connected to a set of scales with a plate in which the volunteers fill their food. It records and stores the weight loss from the plate as the volunteers eat, and tell them when they have more than they should.
The device also measures how quickly a person eats his meals.
"I used to eat very fast. I could eat a very large meal in about three minutes. Now I take about 16 minutes," the Daily Mail quoted Laurence as saying.
"The treatment has given me so much confidence. I feel very good about myself now," he added.
Laurence's mother Lydia has revealed that the weight loss has had a dramatic effect on her son's personality.
"He's a different person. He's confident, he's going out and he's got a great sense of humour. I don't think we've ever really known the real Laurence until now - and it's brilliant," she said.